MUNICH — Vice President Joseph R. Biden Jr. said Saturday that the United States will pursue a missile defense plan that has angered the Kremlin, but he also left open the possibility of compromise on the issue and struck a more conciliatory tone than the Bush administration on relations with Russia.

“It is time to press the reset button and to revisit the many areas where we can and should be working together with Russia,” Mr. Biden said in a speech at a security conference here attended by global leaders and diplomats.

The highly anticipated speech, seen as the first major outline of the new administration’s relations with the world, came just days after Kyrgyzstan’s president announced a decision to close a United States base there that is crucial to the war in Afghanistan, which President Obama has made his top foreign policy priority. That announcement was made in Moscow, and many American officials concluded that the Russians had pressured Kyrgyzstan as part of their campaign to reassert control over former Soviet republics.

Some Western diplomats had expected Mr. Biden to announce a strategic review of the planned missile defense system as a way to defuse tensions between Washington and Moscow. Although Mr. Biden did not go that far, he did leave room in both the speech — and an interview afterward — for unspecified changes in the plan put forward by the Bush administration.

“We will continue to develop missile defenses to counter a growing Iranian capability, provided the technology is proven and it is cost-effective,” Mr. Biden said during the speech.

Foreign policy experts said that the Obama administration was most likely averse to making any outright concessions on the antimissile system just days after the Kyrgyz announcement, fearing it could be interpreted as a sign of weakness. Mr. Biden, they said, seemed to be balancing the need to appear firm with the administration’s hopes to reverse the several-year slide in American-Russian relations. Russian cooperation is considered important to American attempts to keep Iran and North Korea from continuing with their nuclear programs.

The missile defense plan as it had been envisioned by the Bush administration would place missile interceptors in Poland and a radar system in the Czech Republic. The Russians balked at the placement so close to their border, saying it was proof that the system was meant to combat their nuclear arsenal, rather than a missile threat from Iran as President Bush had said. Mr. Biden did not say in his speech where he expected the system to be based.

In an interview after the speech, Mr. Biden declined to say what changes might be considered. “What I did say in the speech is that we would consult with our European allies as well as consult with the Russians,” he said.

A top Obama administration official who spoke on condition of anonymity because of the delicacy of the issue said that the administration had not yet reached the point of discussing whether it could, or would, move the missile defense sites to other countries.

The Russian reaction to Saturday’s speech was quick, and favorable. Konstantin Kosachev, chairman of the international affairs committee in the Duma, the lower house of Parliament, said in an interview that he welcomed Mr. Biden’s comments about “a need to listen to partners,” which Mr. Kosachev contrasted with Mr. Bush’s approach “that everything is already predecided, everything is clear and should be done the way the American administration thinks about it.”

Mr. Kosachev said the new stance would make it easier to reach agreement on many issues, including the antimissile dispute.

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Chancellor Angela Merkel of Germany and President Nicolas Sarkozy of France at the conference in Munich on Saturday.Credit
Michael Dalder/Reuters

Mr. Biden also indicated that the United States would take a nuanced approach toward Iran. He suggested that the administration was willing to be more conciliatory than Mr. Bush had been, but also to continue his tough policies if necessary.

“We are willing to talk to Iran,” Mr. Biden said, in a departure from the Bush administration. But the vice president quickly tacked back to a refrain common during the last years of the Bush presidency and spoke of offering Iran’s leader a choice: “Continue down your current course and there will be pressure and isolation; abandon the illicit nuclear program and your support for terrorism, and there will be meaningful incentives.”

Iran contends its nuclear program is for generating energy; many Western countries see it as a screen for a nuclear weapons program.

It was unclear if Mr. Biden’s refusal to take a clear step back on missile defense Saturday was part of a bargaining strategy in the elaborate chess game being played between the former cold war enemies.

In recent weeks, Russia’s leaders have sent mixed messages: offering kind words about Mr. Obama, then suggesting that the United States would need to do more to win Russia’s support — including addressing complaints about American plans to expand NATO and ending plans for the antimissile defense system as it was conceived by Mr. Bush.

The Kremlin’s relationship with Washington became increasingly frosty in the last several years as Russia began to try to reclaim some of its old power and chafed at what it saw as Bush administration attempts to stymie its efforts. The relations hit a low point during the brief war last summer between Russia and Georgia, an American ally, over the breakaway regions of Abkhazia and South Ossetia. The Russian president, Dmitri A. Medvedev, later recognized the independence of the two enclaves.

On Saturday, Mr. Biden rejected the notion of a Russian regional sphere of influence and said that Mr. Obama would continue to press NATO to seek “deeper cooperation” with like-minded countries.

Although his language was tempered, Mr. Biden said, “We will not agree with Russia on everything.

“For example,” he said, “the United States will not recognize Abkhazia and South Ossetia as independent states. We will not — will not — recognize any nation having a sphere of influence. It will remain our view that sovereign states have the right to make their own decisions and choose their own alliances.”

Mr. Biden’s remarks came a day after Mr. Ivanov told the same group that Moscow would not deploy missiles on the Polish border if the United States reviewed its missile defense plan. Just after Mr. Obama won the presidency last year, Mr. Medvedev promised to place short-range missiles on Russia’s western border if Washington proceeded with its planned missile defense system in Eastern Europe.

But chances for a clear reconciliation between the United States and Russia at this conference dissipated, foreign policy experts said, after the announcement on the Kyrgyz base. Mr. Obama plans to send as many as 30,000 additional troops to Afghanistan over the next two years; shaky overland supply routes through Pakistan would make it difficult for the United States to adjust to the loss of the base.

During the interview Saturday, Mr. Biden said that the United States would find an alternative to the air base. “We have other options,” he said, but he did not elaborate.

Mr. Biden’s speech was the highlight of the security conference. Most of the dignitaries who were gathered seemed primed to hear how the United States and its new leadership viewed the world. They erupted into applause when Mr. Biden walked onto the stage.

It was at this security conference two years ago when the new tension between the United States and Russia leapt to the fore as Vladimir V. Putin, then Russia’s president, lashed out against the United States over its use of force in Iraq.

A version of this article appears in print on , on page A6 of the New York edition with the headline: Biden Signals U.S. Is Open to Deal With Russia on Plan for Missiles. Order Reprints|Today's Paper|Subscribe